The main objective of this study is to evaluate the impact of procedures designed to improve patient compliance in smoking cessation with a nicotine-bearing chewing gum (NCG) regimen. NCG alone has been shown to have compliance problems, so it will be compared to NCG administered with compliance-increasing techniques. Sixty physicians will be divided into "NCG alone" or "NCG plus" compliance groups. Followups will assess adherence to the program and success in smoking cessation. This phase of the study will involve about 2520 patients. An additional 360 patients will participate in a side study to assess measures such as continual urges to smoke, relapses, and reactions to gum use. The investigation of physician compliance behavior is proposed by the Department of Health Studies at the University of Waterloo (Ontario, Canada) and by the Department of Family Medicine at McMaster University. While behavioral science expertise exists at the former institution, McMaster will provide personnel with backgrounds in family medicine and in clinical epidemiology. The consortium plans to manage the proposed study by using a management committee of four key persons, who will meet regularly to monitor all aspects of the study. In addition, internal and external consultants are proposed. Because nicotine gum has been approved for prescription in Canada for some four years, this randomized clinical trial proposes study of several questions related to physician compliance over time: 1) although efficacy of the gum has been established, what is its effectiveness; 2) will specific instructions given by the physician and a series of follow-up appointments be more effective in eliciting smoking cessation in this "usual case" environment, e.g., where nicotine gum is no longer noteworthy; and 3) will the planned formative and process evaluations confirm physician behavior, and provide clues why certain procedures were more effective. For the validation of the smoking cessation all volunteers will be recalled one year after program initiation coincident with a point in time six months after the last use of nicotine gum. At that time saliva will be collected and analyzed for cotinine.